This invention relates to motorcylces, and more particularly to a safety device for cutting out a motorcycle engine in the event the rider loses control for any reason.
Motorcycle riders are encouraged to wear protective gear. The most important item is a safety helmet with a plastic face shield attached. Boots and gloves are other important items. In addition to these items, it is recommended that the rider wear a leather jacket and heavy pants, all to protect the body as much as possible in the event of a collision or a spill. These items are particularly important in races, rallies, trail riding and hill climbing when the rider can be expected to test the limits of his skill from time to time such that a spill can be expected. However, except for the helmet, these items provide only limited protection against abrasions.
Once the rider leaves his motorcycle, in a collision or a spill, the uncontrolled vehicle becomes a lethal instrument endangering the spilled rider and others. The level of danger is greatly reduced if the rider is able to kill the engine as he leaves the motorcycle. Some motorcycles are equipped with a cut-out switch on the right handlebar just forward of the starter switch, but that is only for convenience in a controlled stop. It is not reasonable to expect the rider to use it in a collision or a spill.
The high level of danger is due not just to the momentum of the motorcycle carrying it into other persons or vehicles, but due to the fact that the engine is still running and engaged. Most motorcycles have a spring biased throttle which cuts the engine back to idle when the throttle grip is released, but the throttle cable or linkage often jams in the open position, and even at idle speed the chain and driven wheel turn at a significantly high speed.
The drive chain and driven wheel of a riderless motorcycle are a menace to everyone around, particularly the fallen rider since he is likely to become entangled with the chain or wheel. On off-road motorcycles of the type for trail riding and hill climbing, the tires have tread designs that are particularly knobby. Consequently, the tire of the driven wheel can itself inflict grave injury, particularly if it wedges some limb of the rider between the tire and the motorcycle fender or frame. The driving chain is, of course, always a lethal instrument; it is a virtual chain saw that will easily cut through leather and heavy garments.
In the past, I have experimented with the use of a safety switch functionally like a cut-out switch, but arranged to close a ground contact to the ignition coil when an insulating tab (connected to the wrist of the rider with a lanyard) is pulled out automatically upon the rider losing his grip on the handle bar. One arrangement I have used consists of biasing one end of a metal strip against the handlebar, as with a rubber band midway between the two ends. The other end is insulated from the handlebar and connected to the ignition coil. The one end against the handlebar is lifted and the insulating tab is inserted. Friction holds the inserted tab in place until yanked out by the lanyard. While this safety cut-out switch is effective, there is a problem of holding the tab in place under extreme vibrations.
To make the task of inserting the tab easier, I have experimented with a design involving two leaf springs biased against each other, but bent outwardly away from each other at their ends. While this does make insertion of the tab easier, the problem of keeping the tab in place is made more difficult since the tab is now in a protruding position normal to the handle bar. There is also the problem that it is too easily disengaged temporarily, as by bending one leaf spring away beyond its elastic limits to a position where it is no longer normally in contact with the other leaf spring. While it can be restored to its normal position by bending it back, the purpose of the safety device is in the meantime defeated. In other words, a rider may easily disengage the cut-out switch; but that next ride may be the very time it is needed.